Method and apparatus for sending and receiving ethernet physical-layer oam overhead

ABSTRACT

A method and an apparatus for sending an Ethernet physical-layer OAM overhead, and a method and an apparatus for receiving an Ethernet physical-layer OAM overhead are disclosed herein. A method for sending an Ethernet physical-layer OAM overhead includes: adjusting the order of sending a payload block and part of Inter-Packet Gaps (IPGs) in a data stream to be transmitted; and when receiving a request for sending an OAM overhead, substituting the OAM overhead for the part of IPGs, and sending the OAM overhead before sending the payload block. Through the present invention, the order of sending IPGs and payload blocks in an MAC data stream can be adjusted, and the OAM overhead can be sent in time.

This application is a continuation of International Application No.PCT/CN2008/072949, filed on Nov. 5, 2008, which claims priority toChinese Patent Application No. 200710170315.0, filed on 12 Nov. 2007,both of which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the Ethernet physical-layer technicalspecifications, and in particular, to a method and an apparatus forsending an Ethernet physical-layer Operation Administration Maintenance(OAM) overhead, and a method and an apparatus for receiving an Ethernetphysical-layer OAM overhead.

BACKGROUND

For a long time, the Ethernet has been widely applied due to costefficiency. With the progress of time and technology, the Ethernetevolves to a 100G rate. Currently, the 100G Ethernet (100GE) is understandardization. The Institute of Electrical and Electronic EngineersHigher Speed Study Group (IEEE HSSG) has specified the requirements forthe High Speed Ethernet (HSE) with a rate higher than 10G, and definesthe subsequent standards to be formulated in view of the marketpotentiality, technical maturity, and cost efficiency. As limited by thetechnical difficulty and cost efficiency, the 100GE will evolve frommulti-lane to single-lane in the future.

FIG. 1 shows a model of a multi-lane HSE. As shown in FIG. 1, themulti-lane HSE includes: a Media Access Control (MAC) module, adapted togenerate MAC data; a Reconciliation Sublayer (RS) module, which is alane between the MAC module and the physical-layer module; a PhysicalBinding Layer (PBL) module, adapted to distribute and convergemulti-lane data; a Physical Coding Sublayer (PCS) module, adapted toencode the data from the MAC module; a Physical Medium Attachment (PMA)module, adapted to convert codes into bit streams suitable for beingtransmitted on the physical layer, and synchronize the data decoding; aPhysical Medium-Dependent (PMD) module, adapted to transmit signals,amplify and modulate signals, and rectify waves; and a Medium-DependentInterface (MDI), which defines the connector type corresponding todifferent physical media and PMD devices. The 100 GigabitMedium-Independent Interface (CGMII) is a high-speed interface.Generally, based on the processing rate of the existing components, thepossible bit width of the CGMII interface of the multi-lane 100GE is 640bits or 320 bits.

The Ethernet physical-layer OAM overhead is adapted to provide theconnectivity monitoring and fault management for the entire link of theEthernet. The OAM overhead may be encapsulated in an Inter-Packet Gap(IPG) for transmission. The IPG is generated when the MAC sublayer sendsMAC frame data. In the prior art, after the MAC sublayer sends acomplete MAC frame, the MAC sublayer cannot send the next MAC framebefore expiry of a gap required for sending 96 bits of data. The gap iscalled Inter-Frame Gap (IFG) on the MAC sublayer, and is called an IPGon the MII and the physical sublayer. Because the minimum IFG alone isdefined, the period, in which no data is available for sending after acomplete MAC frame is sent, is also regarded as an IFG; and correspondsto the lower-layer IPG. The IPG reflects the data transmitted in theinterval in which the physical layer stops sending the MAC frame data.

In the method for sending the OAM overhead in the prior art, if an OAMoverhead needs to be sent while an MAC frame is being transmitted, it isnecessary to wait until completion of sending the MAC frame, and thenthe OAM overhead is sent in the subsequent IPG. The detailed steps aredescribed below:

Step 1: The data streams to be sent are sequentially received, and anIPG or a payload block in the data stream is sent in the time of everybeat. The MAC data stream includes MAC frames and IPGs. As shown in 2 a,the MAC frame is payload data in the data stream, and an MAC frameincludes several payload blocks. For example, the first MAC frameincludes a payload block a and a payload block b, and the second MACframe includes a payload block c, a payload block d, and a payload blocke. An IPG1 exists between the first MAC frame and the second MAC frame,namely, between the payload block b and the payload block c.

Step 2: MAC data streams are received sequentially. When the payloadblock b is received, a request for providing an IPG is received. The IPGis used to send an OAM overhead. As shown in FIG. 2 b, a request forproviding an IPG is received in the process of receiving the payloadblock b.

Step 3: The payload block a and the payload block b are sent, as shownin FIG. 2. In this step, no IPG is available for sending the OAMoverhead, and it is necessary to wait to see whether the next beat is anIPG.

Step 4: The IPG1 after the payload block b is used to send the OAMoverhead, as shown in FIG. 2 d.

Step 5: The subsequent payload blocks c, d, and e are sequentially sent,as shown in FIG. 2 e.

In the preceding process, after an IPG request is received, whichrequests for an IPG for sending the OAM overhead, it is necessary towait for sending the OAM overhead. That is, the OAM overhead is sent byusing the subsequent IPG only when the sending of the MAC frame iscomplete. This causes that the OAM overhead cannot be sent in time.

SUMMARY

The embodiments of the present invention provide a method and anapparatus for sending an Ethernet physical-layer OAM overhead, and amethod and an apparatus for receiving an Ethernet physical-layer OAMoverhead, to send the OAM overhead in time.

A method and an apparatus for sending an Ethernet physical-layer OAMoverhead in an embodiment of the present invention are implementedthrough the following technical solution:

A method for sending an Ethernet physical-layer OAM overhead includes:

adjusting the order of sending payload blocks and part of IPGs in a datastream to be transmitted; and

when receiving a request for sending an OAM overhead, substituting theOAM overhead for the part of IPGs, and sending the OAM overhead beforesending the payload blocks.

A method for sending an Ethernet physical-layer OAM overhead includes:

when forwarding payload blocks in a data stream, if a request forproviding an IPG is received, storing the payload blocks ready forforwarding into a buffer, and using the OAM overhead as the datacurrently to be sent.

An apparatus for sending an Ethernet physical-layer OAM overheadincludes: a reconciling module, a data buffer, an IPG buffer, and atleast one OAM sending module.

The reconciling module is adapted to store part of IPGs in a receiveddata stream into the IPG buffer, and store payload blocks and theremaining IPGs in the received data stream into the data buffer; sendthe IPGs in the IPG buffer to the OAM sending module, and then send thepayload blocks and the remaining IPGs in the data buffer to the OAMsending module.

The data buffer is adapted to store the payload blocks and the remainingIPGs.

The IPG buffer is adapted to store part of the IPGs.

The OAM sending module is adapted to substitute the OAM overhead for thepart of the IPGs, send the OAM overhead, and then send the IPGs and thepayload blocks in the data buffer.

An apparatus for sending an Ethernet physical-layer OAM overheadincludes: a reconciling module, a buffer, and at least one OAM sendingmodule.

The reconciling module is adapted to store the payload blocks ready forforwarding into the buffer, and use the OAM overhead as the datacurrently to be sent.

The buffer is adapted to store the payload blocks.

The OAM sending module is adapted to send the OAM overhead and then sendthe payload blocks in the buffer.

In the technical solution under the present invention, by adjusting theorder of the payload blocks and part of IPGs in the data stream, theIPGs are instantly available for sending the OAM overhead, and then thepayload blocks and the remaining IPGs are sent. In this way, the OAMoverhead is sent in time.

BRIEF DESCRIPTION OF THE DRAWINGS

To make the technical solution under the present invention or the priorart clearer, the accompanying drawings for illustrating the embodimentsof the present invention or the prior art are outlined below. Evidently,the accompanying drawings are for the exemplary purpose only, and thoseskilled in the art can derive other drawings from such accompanyingdrawings without making any creative effort.

FIG. 1 shows a multi-lane high-speed Ethernet model in the prior art;

FIG. 2 a to FIG. 2 e show a method for sending an OAM overhead in theprior art;

FIG. 3 is a flowchart of a sending method in the first embodiment of thepresent invention;

FIG. 4 shows a data stream finally sent in the sending method in anembodiment of the present invention;

FIG. 5 is a flowchart of a sending method in the second embodiment ofthe present invention;

FIG. 6 a to FIG. 6 d show data streams corresponding to different stepsin a sending method in the second embodiment of the present invention;

FIG. 7 is a flowchart of a receiving method in an embodiment of thepresent invention;

FIG. 8 shows a sending apparatus in the first embodiment of the presentinvention;

FIG. 9 is a block diagram of a sending apparatus in the secondembodiment of the present invention; and

FIG. 10 is a block diagram of a receiving apparatus in an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present invention provide a method for sending anEthernet physical-layer OAM overhead to adjust the order of sending thepayload blocks and part of IPGs in the MAC data stream, and send the OAMoverhead before sending the payload blocks.

In the prior art, an MAC frame length is variable. Although it isstipulated that the minimum gap between adjacent MAC frames is 96 bits,the IPG traffic is very low when the MAC frame length is the maximumvalue in the variable range. For example, the prior art stipulates thatthe minimum gap is 96 bits; when the MAC frame length is the maximumvalue of 1500 bytes, the IPG traffic is 1G×96/(96+1500×8) for a 1GEthernet. In this case, because the MAC frame length is the maximumvalue of 1500 bytes, the IPG traffic is the minimum value, and the IPGmay be not enough for sending the OAM overhead.

The technical solution under the present invention is expounded belowwith reference to the accompanying drawings. Evidently, the embodimentsprovided herein are for the exemplary purpose only, and are not all ofthe embodiments of the present invention. Those skilled in the art canderive other embodiments from the embodiments provided herein withoutmaking any creative effort, and all such embodiments are covered in theprotection scope of the present invention.

To make the technical solution under the present invention clearer tothose skilled in the art, the following describes the embodiments of thepresent invention in more detail with reference to the accompanyingdrawings.

As shown in FIG. 3, the method in the first embodiment of the presentinvention includes the following steps:

Step 301: The order of sending payload blocks and part of IPGs in a datastream is adjusted.

Specifically, the RS module receives a data stream, stores part of theIPGs in the data stream into an IPG buffer, and stores the payloadblocks and the remaining IPGs in the data stream into the data buffer.

The process of storing part of IPGs in the data stream into the IPGbuffer and storing the payload blocks and the remaining IPGs in the datastream into the data buffer includes:

when the number of IPGs stored in the IPG buffer reaches or exceeds thepreset upper threshold, writing all IPGs in the received data streaminto the data buffer; and

when the number of IPGs stored in the IPG buffer is less than the presetupper threshold, writing all IPGs in the received data stream into theIPG buffer.

When the number of IPGs stored in the IPG buffer reaches or exceeds thepreset upper threshold, it indicates that the IPG buffer has enough IPGsfor sending the OAM overhead. In this case, the IPGs in the data streamdo not need to be stored into the IPG buffer, but all the IPGs in thedata stream are all stored into the data buffer.

Conversely, when the number of IPGs stored in the IPG buffer is lessthan the preset upper threshold, the IPGs in the received data streamare stored into the IPG buffer. The payload block in the data stream isstored into the data buffer.

Step 302: When receiving a request for sending an OAM overhead, the partof IPGs are replaced with the OAM overhead, and the OAM overhead is sentbefore the payload blocks are sent.

In practice, a tag may be affixed to the IPG removed out of the IPGbuffer, and then the IPG is sent to the OAM sending module. Accordingly,the OAM sending module substitutes the OAM overhead for the tagged partof the IPG OAM overhead, sends the OAM overhead, and forwards the IPGsand the payload block sent from the RS module and stored in the databuffer.

In the preceding step, the RS module can provide the IPG in the IPGbuffer when receiving a request for the IPG In this way, the order ofsending IPGs and the payload blocks in the data stream is adjusted, andthe OAM overhead is sent in time.

The preceding step further includes: notifying the MAC module to reducethe rate of the payload blocks in the data stream when the number ofIPGs in the IPG buffer is less than the preset less threshold. When thenumber of IPGs stored in the IPG buffer is less than the preset lessthreshold; it indicates that the IPG buffer lacks the IPG for sendingthe OAM overhead. In this case, the MAC module is notified to reduce therate of the payload blocks in the data stream, and the IPGs in the datastream increase accordingly. Therefore, more IPGs are stored in the IPGbuffer to meet the requirements of sending more OAM overheads.

The MAC module reduces the rate of sending the data stream. For example,when the total rate is 100 Gbit/s (100 Gbit/s is abbreviated as 100G andother rate-related expressions are similar to this), the rate of thepayload blocks of the MAC frame sent by the MAC module to the RS moduleis 99.56, and therefore, the IPG rate is 0.5G If a 0.6G OAM overheadneeds to be sent at this time, because 0.5G is less than 0.6G the rateis not enough if the IPG is replaced with the OAM overhead simply. Inthis case, the rate of the payload blocks sent by the MAC module to theRS module needs to be reduced, for example, the rate is reduced to99.4G, and therefore, the rate of the IPG sent by the MAC module to theRS module is 0.6G which is enough for sending the 0.6G OAM overhead.Reducing the rate of the payload blocks from 99.5G to 99.4G is abackpressure process. The backpressure aims to reduce the rate ofpayload blocks and generate more IPGs.

When the number of IPGs in the IPG buffer reaches or exceeds the presetlower threshold, it indicates that the IPGs stored in the IPG buffer areenough for sending the OAM overhead. In this case, the MAC module may benotified not to reduce the rate of the payload blocks in the datastream.

Provided below is a complete example of the first embodiment of themethod.

Step A: When the number of IPGs in the IPG buffer reaches or exceeds thepreset upper threshold, the IPGs in the data stream are written into thedata buffer; when the number of IPGs in the IPG buffer is less than thepreset upper threshold, the IPGs in the data stream are written into theIPG buffer.

It is assumed that the data stream includes a first MAC frame, an IPG1,and a second MAC frame, as shown in FIG. 2 a. The first MAC frameincludes a payload block a and a payload block b. The second MAC frameincludes a payload block c, a payload block d, and a payload block e.

It is assumed that the number of IPGs in the IPG buffer is less than thepreset upper threshold. After step A, the IPG buffer includes IPG1; thedata buffer includes the payload block a and the payload block b of thefirst MAC frame, and includes the payload block c, the payload block dand the payload block e of the second MAC frame.

Step B: The RS module receives the request for providing IPGs, andremoves the IPG1 in the IPG buffer and sends it to the OAM sendingmodule.

Step C: The OAM sending module replaces the IPG1 with the OAM overheadto be sent, sends the OAM overhead, and then forwards the payload blockb in the first MAC frame, and the payload block c, payload block d, andpayload block e in the second MAC frame, where the MAC frames are sentby the RS module and stored in the data buffer. The forwarded datastream is shown in FIG. 4.

Provided below is the second method embodiment of the present invention.As shown in FIG. 5, the method in the second embodiment of the presentinvention includes the following steps:

Step 501: The RS module receives a request for providing IPGs whenforwarding the payload block in the data stream.

The requested IPGs are used for sending OAM overheads.

More specifically, this step may include step 501 a and step 501 b:

Step 501 a: The RS module forwards the payload block in the data stream.It is assumed that the data stream includes a first MAC frame, an IPG1,and a second MAC frame, as shown in FIG. 6 a. The first MAC frameincludes a payload block a and a payload block b. The second MAC frameincludes a payload block c, a payload block d, and a payload block e.The RS module receives a request for providing IPGs when forwarding thepayload block in the MAC data stream, for example, when forwarding thepayload block b.

Step 501 b: The OAM generating module responds to the request forsending OAM overhead, which is sent by the OAM control-plane module. Theresponse requests the RS module to provide the IPGs required for sendingthe OAM overhead.

Step 502: The payload block ready for forwarding is stored into thebuffer, and the OAM overhead is used as the data currently to be sent.

As shown in FIG. 6 b, the payload block b is stored into the buffer, andthe RS module generates an extra IPG; namely, IPG b in FIG. 6 b, andsends the IPG b to the OAM sending module.

As shown in FIG. 6 c, the RS module uses the IPG1 in the forwardedsubsequent data stream to send the payload block b in the buffer to theOAM sending module. The OAM sending module forwards the payload block b,and forwards the subsequent data stream, for example, payload block c,payload block d, and payload block e in FIG. 6 c. The finally sent datastream is shown in FIG. 4.

In the preceding step, after receiving the request for providing IPGs,the RS module stores the forwarded payload block in the data stream intothe data buffer, uses the OAM overhead as the data currently to be sent,and sends the OAM overhead. Then, the RS module sends the payload blockand the subsequent data stream in the data buffer. In this way, theorder of sending the IPGs and the payload block in the data stream isadjusted, and the OAM overhead is sent in time.

The preceding step may further includes: notifying the MAC module toreduce the rate of the payload blocks in the data stream when the numberof payload blocks in the buffer reaches or exceeds the preset upperthreshold.

When the number of payload blocks in the buffer reaches or exceeds thepreset upper threshold, it indicates that the buffer is not enough forstoring the payload blocks in the data stream, and no enough extra IPGscan be generated. In this case, the MAC module is notified to reduce therate of the payload blocks in the data stream, and the IPGs in the datastreams are increased accordingly. Therefore, the buffer has more spacefor storing the payload blocks, and can generate more extra IPGs to meetthe requirement of sending more OAM overheads.

In the first method embodiment and the second method embodiment, the OAMoverhead sent by the OAM sending module can be sent in different lanesindependently, thus implementing connectivity monitoring and faultmanagement for different lanes of the Ethernet.

Provided below is an embodiment of a receiving method in the presentinvention.

As shown in FIG. 7, a receiving method in an embodiment of the presentinvention includes the following steps:

Step 701: The OAM detecting and retrieving module detects the datastream, and retrieves the OAM overhead when discovering an OAM overheadin the data stream.

The OAM overhead has the code block characteristics different from thepayload block in the data stream. Therefore, the OAM detecting andretrieving module may detect the code block characteristics in the datastream, and retrieve the OAM overhead.

Step 702: The OAM receiving and processing module receives the OAMoverhead retrieved by the OAM detecting and retrieving module, andsubmits the OAM overhead to the OAM control-plane module for processing.

In this step, the OAM detecting and retrieving module sends theretrieved OAM overhead to the OAM receiving and processing module. Afterthe OAM receiving and processing module processes the OAM overhead, theOAM control plane at the receiver performs the corresponding monitoringand management functions.

Step 703: The RS module receives and forwards the data stream to the MACmodule, and adapts the transmission rate of the data stream of the MACmodule by inserting IPGs or deleting IPGs.

In the preceding embodiment, the data stream received at the receiverhas enough OAM overhead information. By retrieving the OAM overhead, theOAM control-plane module can receive the OAM overhead informationcorrectly and perform the corresponding operations. If the OAM overheadis sent independently in different lanes, the receiver can monitor andmanage every lane according to the received OAM overhead.

Provided below is the first embodiment of a sending apparatus in thepresent invention. FIG. 8 is a block diagram of a sending apparatus inthe first embodiment of the present invention.

An apparatus for sending an Ethernet physical-layer OAM overheadincludes: an MAC module 801, a reconciling module 802, a data buffer803, an IPG buffer 804, an OAM generating module 805, at least one OAMsending module 806, and at least one PCS/PMA/PMD module 807.

The MAC module 801 is adapted to generate a data stream which includespayload blocks and IPGs.

The reconciling module 802 is adapted to receive data streams, storepart of IPGs in the data stream into the IPG buffer 804, and store theremaining IPGs and the payload blocks in the data stream into the databuffer 803; receive the request for providing IPGs from the OAMgenerating module 805, retrieve the IPGs from the IPG buffer 804, andsend the IPGs to the OAM sending module 806.

The data buffer 803 is adapted to store the payload blocks and the IPGs.

The IPG buffer 804 is adapted to store the IPGs.

The OAM generating module 805 is adapted to generate the OAM overhead,and request the reconciling module 802 to provide the IPGs.

The OAM sending module 806 is adapted to use the IPGs in the IPG buffer804 to send the OAM overhead to the PCS/PMA/PMD module 807, and forwardthe IPGs and the payload blocks sent by the reconciling module 802 andstored in the data buffer 803 to the PCS/PMA/PMD module 807.

The PCS/PMA/PMD module 807 is adapted to process and forward the OAMoverhead and the payload blocks. The processing may include: encoding,decoding, scrambling/descrambling, serial-parallel/parallel-serialconversion, and optical-electrical/electrical-optical conversion.

When the number of IPGs stored in the IPG buffer 804 reaches or exceedsthe preset upper threshold, the reconciling module 802 writes the IPGsin the data stream into the data buffer.

When the number of IPGs stored in the IPG buffer 804 is less than thepreset upper threshold, the reconciling module writes the IPGs in thedata stream into the extra IPG buffer 804.

The reconciling module 802 is further adapted to notify the MAC module801 to reduce the rate of the payload blocks in the data stream when thenumber of IPGs in the IPG buffer 804 is less than the preset lowerthreshold.

The reconciling module 802 is further adapted to notify the MAC module801 not to reduce the rate of the payload blocks in the data stream anymore when the number of IPGs in the IPG buffer 804 reaches or exceedsthe preset lower threshold.

The method for using the preceding receiving apparatus to receive theOAM overhead is similar to the preceding receiving method.

Provided below is the second embodiment of a sending apparatus in thepresent invention. FIG. 9 is a block diagram of a sending apparatus inthe second embodiment of the present invention.

An apparatus for sending an Ethernet physical-layer OAM overheadincludes: an MAC module 901, a reconciling module 902, a buffer 903, anOAM generating module 904, at least one OAM sending module 905, and atleast one PCS/PMA/PMD module 906.

The MAC module 901 is adapted to generate a data stream which includespayload blocks and IPGs.

The reconciling module 902 is adapted to receive the request forproviding IPGs from the OAM generating module 904 when forwarding thepayload blocks in the data stream, store the forwarded payload blocks inthe data stream into the buffer 903, generate an extra IPG, and send theextra IPG to the OAM sending module 905.

The buffer 903 is adapted to store the payload blocks.

The OAM generating module 904 is adapted to generate the OAM overhead,and request the reconciling module 902 to provide the IPGs.

The OAM sending module 905 is adapted to store the payload blocks readyfor forwarding into the buffer, use the OAM overhead as the datacurrently to be sent, and forward the IPGs and the payload blocks storedin the data buffer and sent by the reconciling module 902 to thePCS/PMA/PMD module 906.

The PCS/PMA/PMD module 906 is adapted to process and forward the OAMoverhead, the payload blocks in the buffer, and the data stream.

When the number of payload blocks in the buffer 903 reaches or exceedsthe preset upper threshold, the reconciling module 902 is furtheradapted to notify the MAC module 901 to reduce the rate of the payloadblocks in the data stream.

When the number of payload blocks in the buffer 903 is less than thepreset lower threshold, the reconciling module 902 is further adapted tonotify the MAC module 901 not to reduce the rate of the payload blocksin the data stream.

The method for using the preceding sending apparatus to send the OAMoverhead is similar to the preceding sending method.

Provided below is an embodiment of a receiving apparatus in the presentinvention. FIG. 10 is a block diagram of the receiving apparatus.

An apparatus for receiving an Ethernet physical-layer OAM overheadincludes: at least one PCS/PMA/PMD module 101, at least one OAMdetecting and retrieving module 102, an OAM receiving and processingmodule 103, a reconciling module 104, and an MAC module 105.

The PCS/PMA/PMD module 101 is adapted to forward the received datastream to the OAM detecting and retrieving module, where the data streamincludes MAC frame data, OAM overhead, and IPGs.

The OAM detecting and retrieving module 102 is adapted to detect thedata stream, and retrieve the OAM overhead when discovering an OAMoverhead in the data stream.

The OAM receiving and processing module 103 is adapted to receive theOAM overhead sent by the OAM detecting and retrieving module, and submitthe OAM overhead to the OAM control-plane module for processing.

The reconciling module 104 is adapted to forward the data stream to theMAC module, and adapt the transmission rate of the data stream of theMAC module by inserting or deleting IPGs.

After being retrieved by the OAM detecting and retrieving module, theOAM overhead in the data stream becomes an IPG, and is still located inthe data stream forwarded by the reconciling module.

The MAC module 105 is adapted to receive the data stream sent by thereconciling module 104.

The method for using the preceding receiving apparatus to receive theOAM overhead is similar to the preceding receiving method.

Although the invention has been described through several preferredembodiments, the invention is not limited to such embodiments. It isapparent that those skilled in the art can make modifications andvariations to the invention without departing from the spirit and scopeof the invention. The invention is intended to cover the modificationsand variations provided that they fall in the scope of protectiondefined by the following claims or their equivalents.

The embodiments of the present invention may be described in ordinarycontexts of computer-executable instructions, for example, a programmodule. Generally, the program module includes routines, programs,objects, components, and data structures which execute a specific taskor implement a specific abstract data type. The embodiments of thepresent invention may also be implemented in a distributed computationenvironment, in which the tasks are performed by remote processingdevices connected through a communications network. In the distributedcomputation environment, the program module may be located in local andremote computer storage media such as a storage device.

Based on the descriptions of the preceding embodiments, those skilled inthe art may understand that the present invention may be implemented bysoftware and a necessary universal hardware platform. Therefore, theessence of the technical solution under the present invention or thecontributions to the prior art may be embodied as a software product.The software product may be stored in a computer-readable storage medium(for example, ROM/RAM, magnetic disk, or CD) and may incorporate severalinstructions for instructing a computer device (for example, a personalcomputer, a server, or a network device) to execute the method specifiedin all or part of the embodiments of the present invention.

1. A method for sending an Ethernet physical-layer OperationAdministration Maintenance (OAM) overhead, comprising: receiving arequest to send an OAM overhead while payload blocks are being forwardedto a data stream, storing the payload blocks for forwarding into abuffer, and communicating the requested OAM overhead before the storedpayload blocks.
 2. The method of claim 1, further comprising:communicating the payload blocks stored in the buffer after the OAMoverhead is communicated.
 3. The method of claim 1, further comprising:reducing a rate of the payload blocks in the data stream when the numberof payload blocks in the buffer reaches a preset upper threshold.
 4. Amethod for sending an Ethernet physical-layer Operation AdministrationMaintenance (OAM) overhead, comprising: adjusting a communication orderin which payload blocks and part of Inter-Packet Gaps (IPGs) aretransmitted into the data stream; and substituting the OAM overhead forthe part of the IPGs a request for communication of OAM overhead isreceived, and sending the OAM overhead before sending the payloadblocks.
 5. The method of claim 4, further comprising: communicating thepayload blocks and remaining IPGs in the data stream after sending theOAM overhead.
 6. The method of claim 4, wherein the adjusting of theorder of sending the payload blocks and the part of the IPGs in the datastream comprises: storing the part of the IPGs in the data stream intoan IPG buffer and storing the payload blocks and remaining IPGs in thedata stream into a data buffer.
 7. The method of claim 6, wherein thestoring of the part of the IPGs in the data stream into the IPG bufferand storing the payload blocks and the remaining IPGs in the data streaminto the data buffer comprises: writing all IPGs in the received datastream into the data buffer when the number of IPGs stored in the IPGbuffer reaches or exceeds a preset upper threshold; and storing thepayload blocks in the data stream into the data buffer.
 8. The method ofclaim 5, further comprising: reducing a rate of the payload blocks inthe data stream when the number of IPGs stored in an IPG buffer is lessthan a preset lower threshold.
 9. An apparatus for sending an Ethernetphysical-layer Operation Administration Maintenance (OAM) overhead,comprising: a data buffer, configured to store payload blocks andInter-Packet Gaps (IPGs); an IPG buffer, configured to store IPGs; areconciling module, configured to store part of IPGs in a received datastream into an IPG buffer and store payload blocks and remaining IPGs inthe data stream into the data buffer; and at least one OAM sendingmodule, configured to substitute an OAM overhead for the IPGs stored inthe IPG buffer, and send the OAM overhead.
 10. The sending apparatus ofclaim 9, wherein: the reconciling module is further configured to sendthe IPGs in the IPG buffer to the OAM sending module, and then send thepayload blocks and the remaining IPGs in the data buffer to the OAMsending module.
 11. The sending apparatus of claim 9, wherein: when thenumber of IPGs stored in the IPG buffer reaches or exceeds a presetupper threshold, the reconciling module writes all IPGs in the receiveddata stream into the data buffer.
 12. The sending apparatus of claim 9,wherein: when the number of extra IPGs stored in the IPG buffer is lessthan a preset lower threshold, the reconciling module is further adaptedto reduce a rate of the payload blocks in the data stream.
 13. Anapparatus for sending an Ethernet physical-layer OperationAdministration Maintenance (OAM) overhead, comprising: a reconcilingmodule, configured to store payload blocks ready for forwarding into abuffer, and use an OAM overhead as data currently to be sent; thebuffer, adapted to store the payload blocks; at least one OAM sendingmodule, adapted to send the OAM overhead and then send the payloadblocks in the buffer.
 14. The sending apparatus of claim 13, wherein:when the number of payload blocks in the buffer reaches or exceeds apreset upper threshold, the reconciling module is further adapted toreduce a rate of payload blocks in a data stream.